#include <stdio.h>
int main() {
    int units;
    scanf("%d",&units);
    if (units < 0) {
        printf("Invalid input");
        return 0;
    }
    float bill = 0;
    if (units <= 100) {
        bill = units * 10;
    } else if ( units <= 200) {
        bill = 100 * 10 + (units - 100) * 15;
        } else {
            bill = 100 * 10 + 100 * 15 + (units - 200) * 20 ;
        }
        printf("%.OF", bill);
        return 0;
}